1. Field of the Invention
The present invention relates to an antiskid brake control system wherein when there is a tendency of a vehicle wheel to lock at the time of braking the vehicle, the action of an actuator causes a brake pressure to decrease, wherein when the revolution of the wheel has been restored due to such pressure reduction, the brake pressure is revived, and wherein these operations are repeated to prevent the wheel from coming into its lock state.
2. Discussion of Background
FIG. 5 is a drawing to help explain the operation of a conventional antiskid system for a vehicle as disclosed in e.g. Japanese Examined Patent Publication No. 28541/1986. In FIG. 5, reference numeral 101 designates the speed of a wheel. Reference numeral 102 designates the actual speed of a vehicle with the wheel. Reference numeral 103 designates the speed of the vehicle including a slip ratio of x%. Reference numeral 104 designates deceleration in the wheel speed 101. Reference numeral 105 designates a brake pressure.
In the time period between t.sub.2 -t.sub.3, the brake pressure is decreased because the wheel deceleration 104 exceeds a given value .alpha..sub.1, i.e., there is a tendency of the vehicle wheel to lock. After that, in the time period between t.sub.5 -t.sub.6, the brake pressure is gradually increased since the wheel acceleration/deceleration is greater than a given value .alpha..sub.3, which means that the wheel have been free from the tendency to be locked. The conventional antiskid brake control system carries out such control that the braking force is gradually increased after the braking force has been decreased. This creates problems wherein variation in the brake pressure with respect to the optimum braking force is great, and a control time wherein the braking force is controlled in the vicinity of the optimum value is too short to shorten stopping distance by braking.